Anastomoses provide critical alternative routes for blood to flow in case of blockages. When blood vessels connect to form a region of diffuse vascular supply it is called an anastomosis. It also contains nerves that supply the vessel as well as nutrient capillaries ( vasa vasorum) in the larger blood vessels.Ĭapillaries consist of a single layer of endothelial cells with a supporting subendothelium consisting of a basement membrane and connective tissue. It is entirely made of connective tissue. The outer layer is the tunica adventitia and the thickest layer in veins.The tunica media is thicker in the arteries rather than the veins. Veins don't have the external elastic lamina, but only an internal one. The tunica media may (especially in arteries) be rich in vascular smooth muscle, which controls the caliber of the vessel. It consists of circularly arranged elastic fiber, connective tissue, polysaccharide substances, the second and third layer are separated by another thick elastic band called external elastic lamina. The middle layer tunica media is the thickest layer in arteries.
A thin membrane of elastic fibers in the tunica intima run parallel to the vessel. It is a single layer of flat cells ( simple squamous epithelium) glued by a polysaccharide intercellular matrix, surrounded by a thin layer of subendothelial connective tissue interlaced with a number of circularly arranged elastic bands called the internal elastic lamina.
Middle English: from Old French veine, from Latin vena.late Middle English: from Latin arteria, from Greek artēria, probably from airein ‘raise’.
0 kommentar(er)
